trace tcp_input.c:4870
  commands
    collect ofo_possible
    collect ((struct tcp_sock *)sk)->rcv_nxt-((struct tcp_sock *)sk)->rcv_wup
    collect ((struct inet_connection_sock *)sk)->icsk_ack.rcv_mss
    collect ((struct tcp_sock *)sk)->rcv_wnd
    collect ((struct inet_connection_sock *)sk)->icsk_ack.pingpong
    collect ((struct inet_connection_sock *)sk)->icsk_ack.quick
  end
